The present invention relates to blister packaging, such as for the containment and dispensing of fast-dissolving dosage form (FDDF) drug formulations or other forms of medication. More particularly, the present invention relates to a stepped edge blister pack having an enlarged unsealed stepped tab at an edge adjacent to each blister pocket, thus allowing for ease of opening and for reinforcement and accordingly the prevention of undesired undulation.
Medication in forms such as tablets, capsules or caplets has been typically packaged in blister packages or sheets of multiple blister compartments. A base sheet of transparent or opaque plastic, for instance polyvinyl chloride (PVC or PVC type laminates), has a plurality of blister compartments projecting from one face thereof, for containing the unit dosages of medication. Solid units of medication may be deposited into the blister compartments of the base sheet. Alternatively, as explained by Gregory et al., U.S. Pat. No. 4,305,502, the medication may be closed and frozen within the plastic sheet and then dried using a freeze-drying process. Preferably, a liquid suspension is dosed into the pre-formed blister compartments of the base sheet. The base sheet containing the suspension is then cooled by a medium such as liquid nitrogen or carbon dioxide, thereby freezing the contents of the blister compartments. The frozen contents may then be subjected to reduced pressure to complete the freeze drying process.
Finally, a lidding or cover sheet typically comprised at least in part of aluminum foil, is peelably sealed, preferably by a heat sealing process, to the top of the base sheet and perforated about each blister compartment, thus removably enclosing the medication.
To permit the cover sheet over an individual blister compartment to be peeled from the respective portion of the base sheet, a small portion of the edge of the cover sheet may be left unsealed to the base sheet, adjacent to each blister compartment. A patient may thus grasp the unsealed edge and accordingly peel the cover sheet from the base sheet to reveal a unit of medication. For instance, the above-mentioned Gregory et al. patent discloses a pharmaceutical dosage form package comprised of a filmic base sheet having depressions, and a covering sheet adhered to the base sheet except at side portions adjacent to each depression. The Gregory specification states that in those portions, "the covering sheet is not adhered to the filmic material so that the user may start peeling away the covering sheet at these locations." (Col. 4, lines 64-66.)
Recently, developments in the medical field have necessitated an increase in the size of the edge peel tab to allow patients with dexterity difficulties a larger tab to grip and peel. Extending the size of the edge peel tab, however, has been seen to result in blister packs that have severe edge undulation due to uneven shrinkage after the heat sealing process and that are difficult to peel in part due to the tendency of the cover sheet to stick to the plastic base sheet as a result of heat transfer.
Prior art blister packs have never before combined the advantages present in the present invention. This invention presents a blister pack comprised of a base sheet having a plurality of blister compartments formed therein, and also a plurality of extended steps formed in and at the edges thereof, each step being adjacent to one of the blister compartments. A substantially planar lidding foil preferably coterminous with the base sheet is peelably sealed to the base sheet, thus enclosing the blister compartments and providing an edge tab at each step adjacent to each blister compartment. The stepped edge of the base sheet provides useful finger accesses through which each edge tab may be grasped. By grasping the edge tab of the lidding foil at the finger access formed by a step and by peeling the lidding foil from a given blister compartment, a patient may dispense the contents of the given compartment. An extended edge peel tab with a stepped-base feature will thus ease the mechanism by which the package is opened and will accordingly assist in patient compliance.
There is shown in the existing art various forms of blister packs, none of which embodies all of the features and advantages of the present invention. The Moser et al. reference, U.S. Pat. No. 3,941,248, for instance, discloses a tear-open package for tablets comprised of a lower base foil, a cover foil and "grasping recesses" for grasping and removal of the cover foil. Moser does not disclose a stepped-edge configuration like that of the present invention. Rather, the "grasping recesses" of Moser are concealed interiorly beneath the cover foil and cannot be easily reached until an individual tablet package is severed from the overall package or until a centrally positioned strip is severed from the overall package.
Mullen, U.S. Pat No. 3,933,245, discloses an article holding and dispensing container comprised of a tray of blister compartments and a closure means heat-sealed to the tray. The tray and closure means are each scored with horizontal and vertical score lines, thus allowing each individual blister to be severed from an adjacent blister. At each intersection of score lines is a preferably circular depressed area, at which point there is an absence of heat-sealing. Thus, the sheet covering an individual blister can be peeled off either (i) by grasping the sheet at the intersection of the adjacent horizontal and vertical score lines or (ii) by detaching the blister from adjacent blisters and then grasping the sheet at the area of depression. In contrast, the cover sheet in the present invention can be peeled from an individual blister by simply grasping the edge-tab at the finger access and pulling the cover sheet away from the base sheet.
Hellstrom, U.S. Pat. No. 3,472,367, discloses a quick-opening package comprised of a relatively stiff supporting layer, at least one pocket formed in the supporting layer, and a backing layer adhered to the supporting layer. In order to open the enclosed pocket, the package is bent along a line crossing the pocket, thereby rupturing the backing layer over the pocket. The supporting layer is preferably reinforced with a series of flutes or ridges to ensure that the bending occurs in the proper position relative to the pocket. Further, Hellstrom discloses a process of manufacturing this quick-opening package, wherein pockets and flutes are simultaneously stamped onto a continuous strip of blister material, a backing layer is applied, and the resulting strip can be severed or fed from a strip dispenser. The present invention differs from Hellstrom in that the blister compartments of the present invention are not opened by bending the package and rupturing a given blister; rather, a blister compartment made in accordance with the present invention would be opened by peeling the cover sheet from the base sheet, after accessing the cover sheet from the stepped peel tab at the edge of the pack.
Finally, as mentioned above, Gregory et al., U.S. Pat. No. 4,305,502, discloses a pharmaceutical dosage form package comprised of a plastic film blister sheet with depressions for receiving dosage forms, and a laminate cover sheet adhered to it except at edge peel tab areas. The surface of the cover sheet is scored to allow access to the enclosed dosage forms, which are formed in place by freeze-drying. Importantly, the Gregory package does not disclose the stepped edges and associated ease of peeling and reduced edge undulation that is achieved by the present invention.